Chapter 15 - peripheral blood and correlation w/ CBC

components of evaluation of peripheral smear

• WBC estimate

• platelet estimate

• relative proportion of leukocyte types

• cell morphology

source of peripheral blood smear specimens

EDTA tubes (purple), prevents blood from clotting - make multiple slides and plt count more accurate, plt satellitosis; sodium citrate (blue) - used for accurate plt and WBC count in known plt clumper, other counts from EDTA

platelet satellitosis

plts adhere to neutrophils, cause pseudothrombocytopenia (decreased plt), falsely increased WBC count in automated methods

dilution factor of sodium citrate

2.7 ml blood/0.3 ml citrate = 9:1 = 1.1 (reciprocal of dilution)

manual wedge technique

write patient identifiers on slide, drop of blood at one end of slide, use second slide at 45 degree angle to slide into drop then across the slide

features of well-made wedge smear

feathered edge has rainbow appearance when held to light, looks like thumb shape not bullet, 2/3-3/4 of slide length, film is smooth without irregularities

how to dry peripheral smear

heat block or air dry, could use fan but risk of artifcats

types of stain

pure Wright, Wright-Giemsa (gold standard, polychromatic stain)

stain characteristics

methylene blue is basic and stains acidic components (ex RNA)

eosin is acidic and stains basic components (ex hgb, eosinophil granules)

colors of blood cells under microscope

RBC = orange to salmon, WBC nuclei = purple to blue, Neutrophil = pink to tan w/ violet granules, eosinophil = bright orange; if specimen is too old its blue

peripheral smear examination

macroscopic - color, grainy appearance

10x - film quality, distribution of cells

40x - variation in size/shape, select area for differential, WBC estimate

100x oil - count WBC differential, plt estimate, RBC/WBC/plt morphology, inclusions

50x oil - same as 100x for experienced technician

WBC morphological abnormalities

toxic gran (granulation), dohle bodies (area of light blue near edge), reactive lymphs (starburst shape), auer rods (red bar)

platelet estimate

under 100x count all plts in 10 fields, take average, multiply by 20,000

CBC results summarized

WBC - total, differential %, # (absolute count), morphology

RBC - total, hgb, hct, MCV, MCH, MCHC, RDW, morphology

Plt - total, MPV (indice from analyzer), morphology

how to calculate absolute count

WBC type % x WBC

70% neut, 6.5 WBC = 0.70 × 6.5 = 4.55

which value(s) used to describe RBC size

MCV, RDW; normal 80-100, decreased = microcytic, increased = macrocytic

which value(s) used to describe RBC color

MCHC, decreased = hypochromia, increased = hyperchromia

normal platelet parameters

plt count = 150-450 × 10^9 (increased=thrombocytosis, decreased=thrombocytopenia)

mean plt volume (MPV) = 6.8-10.2

relationship of RBC,WBC,plt w/ pancytopenia/cytosis

all 3 decreased - pancytopenia (developing leukemia)

all 3 increased - pancytosis (polycythemia vera)

platelet morphology

round, grainy, small